This invention generally pertains to motorized tree stump cutting or grinding devices. Most of these devices are either towed or trailered behind a standard commercial vehicle. Most towed-behind devices are positioned for work by the tow vehicle. Such an arrangement performs well for easy access tree stumps but is not practical in more difficult, tight access applications. The trailer-mounted devices are commonly self-propelled and more compact for tight maneuvering. Their compactness and general high center of gravity make them unstable for high speed towing, hence trailering is a must.
These two general types of stump cutters almost all feature a rotating cutting wheel mounted on a boom which is swept from side to side, and up and down by either manual or hydraulic enhanced force. Typically, the cutting wheel-boom assembly is attached to an elongated main frame with a gasoline or diesel engine providing the necessary power.
It becomes apparent that both of these types of stump cutters have inherent advantages and disadvantages. Hence, it follows that a hybrid device that incorporates said advantages and eliminates said disadvantages would prove to be optimal and therefore superior.
As to the general rules or types cited there are two notable exceptions. First, the variable width, self-propelled stump cutter U.S. Pat. No. 4,690,183 issued to D. Eilertson on Sep. 1, 1987. Due to a high center of gravity this device requires a trailer. Width varies from narrow for tight maneuvering to wider to stabilize the device for the stump cutting function. The second is the variable width device U.S. Pat. No. 5,289,859 issued to J. Minton Jr. and J. Barr on Mar. 1, 1994. This device requires no trailer and is capable of variable width. The method utilized to vary width does not remove the device's weight from the tow wheels during transition. It relies on hydro-mechanical force to accomplish transition. This practice is less than optimal when durability, weight and cost consideration are made. Although these devices display advantages they both are less than optimal overall and are lacking several other advanced features.
As a result, it is concluded that the most desirable stump cutting device would be a hybrid of the two most common types available. Again, those are the tow-behind with wide track and extendable tongue and the self-propelled narrow track type. The hybrid must be variable width and self-propelled. Other advantages featured would include a fixed level mounted engine, enclosed machinery housing and ride-on capability to mention just a few.